JPS63283991A - Thermal stencil paper - Google Patents

Abstract

PURPOSE:To obtain a stencil paper with higher quality which is capable of producing a high-density image free of broken characters or blur and is free of trailing of characters or the like due to sticking or other similar defects, by providing a coated polymer layer comprising a mixed resin of ethyl cellulose with nitrocellulose and/or cellulose acetate butyrate as a main constituent, on one side of a porous film material. CONSTITUTION:A coated polyer layer comprising a mixed resin of ethyl cellulose with nitrocellulose and/or cellulose acetate butyrate as a main constituent is provided on one side of a porous film material to constitute a thermal stencil layer. The porous film material is a paper made from natural fibers, synthetic fibers or a mixture thereof or a nonwoven fabric. Ethyl cellulose preferably has an ethoxyl content of 40-50 wt.%. Nitrocellulose preferably has a nitrogen content of 10-20 wt.%. Cellulose acetate butyrate preferably has an acetyl content of 1-15 wt.% and a butyryl content of 20-60 wt.%.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a heat-sensitive stencil paper having a heat-sensitive stencil layer provided on one side of a porous thin material.

[Conventional technology]

Conventionally, heat-sensitive stencil paper is produced by applying adhesive (including adhesive) to a film made in advance by stretching or inflation, such as polyvinylidene chloride film or polyethylene terephthalate (PET) film. It is manufactured by laminating a porous thin sheet material on this coated surface.

The heat-sensitive stencil paper produced by this method is one in which the above-mentioned film and adhesive layer together constitute a heat-sensitive stencil layer, and the plate is made by perforating these by heating,
During printing, this base paper is wrapped around an ink drum,
Printing is performed by supplying ink from the porous thin material side.

By the way, in such a heat-sensitive stencil paper, when the thickness of the heat-sensitive stencil layer becomes thick, it becomes difficult for ink supplied from the porous thin material side to pass through during printing, and heat melting occurs around it during hot perforation. A large amount of the polymer remains, resulting in poor plate-making accuracy and ink smearing during printing, making it impossible to print with high density and clarity, and reducing printing sensitivity and image quality. There are negative effects.

For this reason, it is desirable for the thickness of the heat-sensitive stencil layer to be as thin as possible. By making the thickness of the heat-sensitive stencil layer as thin as possible, the plate-making accuracy increases and printing becomes easier. This also makes it possible to use high-viscosity ink, which allows for high-density and Clear printing, that is, high-quality printing with good sensitivity and image quality, can be achieved.

However, with the conventional heat-sensitive stencil paper, there is a limit to how thin the heat-sensitive stencil layer can be made, and it is difficult to make the heat-sensitive stencil layer thinner.
It has been difficult to make the thickness less than μm, for example, about 1 μm.

The reason for this is that films such as polyvinylidene chloride film and PET film have a thickness of about 2 μm at most, and it is difficult to obtain films as thin as this at a low price due to film-forming technology and demand. This is because it is difficult in terms of quantity, and even if it were available, it would be difficult to uniformly laminate it onto a porous thin sheet material using an adhesive. In addition, as another reason, in order to adhere the above-mentioned membrane forming film to the porous thin material, usually about 0,5
This is because ~3 g/rd (solid content) of adhesive is required, and the total thickness of the heat-sensitive stencil layer becomes accordingly thicker.

Therefore, in view of the above-mentioned problems with the conventional heat-sensitive stencil paper, the inventors have made extensive studies, and as a result, the heat-sensitive stencil layer to be provided on the porous thin material is composed of a coating layer of a thermoplastic polymer. In other words, if the above layer is formed by coating a thermoplastic polymer, problems in terms of film forming technology, laminating technology, and economic efficiency when using the conventional film forming film or adhesive can be solved. It is possible to easily form a very thin heat-sensitive stencil layer of 2 μm or less, usually about 0.1 to 1.5 μm, which was difficult in the past, without any problems, and without any hindrance to thinning the adhesive layer. I have already proposed this as a prior invention to this invention.

The heat-sensitive stencil paper according to this prior invention has a unique structure in which the heat-sensitive stencil layer is composed of a single layer (coating layer) of a thermoplastic polymer without an adhesive layer, unlike the above-mentioned conventional stencil paper. It has many advantages, such as being able to easily make the layer thinner, making it easier to achieve higher quality printing, and being able to manufacture it at a lower cost.

[Problem that the invention seeks to solve]

However, according to subsequent research by the inventors, the heat-sensitive stencil paper according to the above-mentioned prior invention causes sticking during plate-making, that is, when hot perforation for plate-making, thermally molten polymer protrudes around the paper. This may cause problems such as adhesion, and this may cause characters to drag during printing. Furthermore, for those with few such problems, the printing sensitivity tends to be somewhat insufficient, and in this case, it is difficult to print without missing characters or blurring.

Therefore, the present invention further improves the above-mentioned prior invention, and not only enables high-density printing without missing or blurred characters, but also eliminates scratching of characters due to sticking.
The aim is to provide higher quality heat-sensitive stencil paper.

[Means for solving problems]

As a result of intensive studies to achieve the above object, the inventors found that if a combination of two specific resins is used as a thermoplastic polymer to form a polymer coating layer,
In addition to being able to perform high-density printing without missing or blurring characters,
This invention was completed after learning that it was possible to avoid the problem of characters dragging due to sticking and to obtain higher quality heat-sensitive stencil paper.

That is, the present invention provides a heat-sensitive material characterized in that a polymer coating layer mainly composed of a mixed resin of ethyl cellulose, nitrocellulose and/or cellulose acetate butyrate is provided as a heat-sensitive stencil layer on one surface of a porous thin sheet material. This relates to stencil paper.

[Structure and operation of the invention]

Porous thin leaf materials used in this invention include natural fibers such as manila hemp, kozo, and mitsumata, synthetic fibers such as polyester and nylon, and non-woven fabrics made by mixing these materials with a basis weight of 5 to 15 g/rtr. thing,
Or polyester fiber.

Silk screen gauze etc. can be used.

The ethyl cellulose in this invention has an ethoxyl content of 40 to 50% by weight and an average molecular weight of 20.00.
Those in the range of 0 to 200.000 are preferably used. In addition, the nitrocellulose used in combination with this has a nitrogen content of 10 to 20% by weight and an average molecular weight of 20%.
．． 000 to 200.000, cellulose acetate butyrate has an acetyl content of 1 to 15% by weight, a butyryl content of 20 to 60% by weight,
Those having an average molecular weight in the range of 15.000 to ioo, ooo are preferably used.

The mixing ratio of both of the above resins is such that the latter, that is, the proportion of nitrocellulose and/or cellulose acetate butyrate in the total amount of ethylcellulose and nitrocellulose and/or cellulose acetate butyrate is 10 to 60%, Particularly preferably 20 to 40
It is best to adjust the amount by weight. If the amount of nitrocellulose and/or cellulose acetate butyrate is too high, characters may easily break off or fade, and if it is too low, sticking may occur, causing problems such as dragging of characters, etc. , both are unfavorable.

In addition, in this invention, one or more types of other thermoplastic polymers such as polyvinyl acetate may be used in combination with the above-mentioned mixed resin. However, in this case, it is desirable that the amount of the other thermoplastic polymers is suppressed to 20% or less of the total amount.

In addition, in this invention, the above-mentioned mixed resin is provided as a coating layer on one surface of the porous thin sheet material, and at this time, various kinds of antioxidants, lubricants, plasticizers, antistatic agents, etc. are added to the coating layer. Additives may be included if necessary, and the content of these additives is 50% by weight or less of the entire coating layer.

In other words, the coating layer may not only consist of the mixed resin alone, but may also consist mainly of the mixed resin with an appropriate amount of the above-mentioned additives added thereto.

Various methods can be considered for forming a heat-sensitive stencil layer consisting of such a coating layer. However, since the above-mentioned mixed resin is a polymer that is soluble at 25°C at least 1% by weight in an organic solvent that is not compatible with water, a solution in which 1% by weight or more of this mixed resin is dissolved in the above-mentioned organic solvent is prepared. It is most preferable to adopt the method described below. According to this method, a thin and uniform coating can be obtained without penetrating the mixed resin into the porous thin material or causing coating defects such as fish eyes in the coating layer. This is because the coating layer can be easily formed.

This preferred method includes the steps of sufficiently filling the voids of the porous thin sheet material with water, and mixing an organic solvent that is incompatible with water with at least 1% by weight dissolved therein on one side of the water-containing porous thin sheet material. This process consists of a step of applying a solution containing the resin and, if necessary, the other thermoplastic polymers and additives mentioned above, and a step of drying after this application to sequentially remove the above-mentioned organic solvent and water.

In this way, when a porous thin sheet material is filled with water and then a solution of a mixed resin dissolved in an organic solvent that is incompatible with water is applied, the voids in the porous thin sheet material are filled with water. The applied solution forms a layer without penetrating into the voids, and by drying it, it coats the surface of the porous thin material with a thickness of 2 μm or less, usually 0.1 to 1°5 μm.
It is possible to form an extremely thin and uniform polymer coating layer without coating defects such as fish eyes. In addition, by selecting and using porous thin sheet materials and mixed resins that have good affinity for each other, the surface of the porous thin sheet material and the polymer coating layer are physically and chemically bonded at the interface to form a strong bond. It becomes a joined product.

In the above method, the filling of water into the porous thin film material is
This can be done by various methods such as roll coating and dipping, and the polymer solution can be applied by using applicator coating, fountain coating, goo coating, and the like. These methods themselves are not particularly limited.

Organic solvents that are incompatible with water include hexane, cyclohexane, cyclohexene, benzene, toluene, xylene, chloroform, ethyl acetate, methyl ethyl ketone,
Many organic solvents may be mentioned, such as methyl isobutyl ketone. The mixed resin is dissolved in one or more of these organic melting agents, and if necessary, the other thermoplastic polymers and additives mentioned above are added, but the polymer concentration at this time is at least 1% by weight, usually It is desirable to adjust the amount to about 2 to 10% by weight in order to form a thin and uniform coating layer.

Drying conditions after application vary depending on the type of organic solvent, but
Normally, the heating time may be about 1 to 10 minutes at 60 to 120°C. By this drying, first, the organic solvent in the coating layer is volatilized, and then the water filled in the porous thin sheet material is volatilized and removed.

In addition to the above-mentioned methods, methods for forming the coating layer include, for example, directly melting and coating the mixed resin on one surface of the porous thin sheet material, and coating a solution of the mixed resin on a release paper, and then
There is also a method of heat-transferring this onto one surface of a porous thin sheet material without using an adhesive. However, in these cases,
Conditions for melt application and thermal transfer should be appropriately selected to prevent the mixed resin from penetrating into the porous thin material and to prevent coating defects such as fish eyes from occurring in the coated layer.

The heat-sensitive stencil paper of this invention obtained in this way is
If necessary, a release layer for preventing adhesion during plate making and an anti-sticking layer for preventing sticking with a thermal head may be provided on the surface of the polymer coating layer as a heat-sensitive stencil layer.

Plate making and printing using the heat-sensitive stencil paper of the present invention may be carried out according to conventional methods. For example, plate making can be done by placing an offset printing original on the surface of a heat-sensitive stencil layer and perforating it with heat using a commercially available heat-sensitive stencil maker, and for printing, using a commercially available stencil printing machine, the base paper after the stencil printing is transferred to an ink drum. It is sufficient to print while supplying ink from the side of the wrapped, porous, thin sheet material.

〔Effect of the invention〕

The heat-sensitive stencil/base paper of the present invention has a polymer coating layer mainly composed of a mixed resin of ethyl cellulose, nitrocellulose and/or cellulose acetate butyrate on one side of a porous thin material to form a heat-sensitive stencil layer. This not only provides the same advantages as the previous invention, such as higher quality printing due to the thinner heat-sensitive stencil layer, but also enables printing without missing or blurring characters, and also eliminates problems such as characters caused by sticking. This provides a special effect of preventing the occurrence of dragging.

〔Example〕

EXAMPLES Below, examples of the present invention will be described in more detail.

Example 1 A porous tissue paper made of Manila hemp with a basis weight of 9 g/rd was filled with water by a dipping method, and then ethylcellulose (ethoxyl content 48% by weight, average molecular weight 100.000) and nitrocellulose (nitrogen Content 12% by weight, average molecular weight 23.000) and weight ratio 6:
A 2% by weight toluene/methyl isobutyl ketone solution of the mixed resin in step 4 was applied using an applicator with a slit thickness of 50 μm, and then dried at 80° C. for 1 minute to form a heat-sensitive stencil layer made of the above mixed resin with a thickness of about 1 μm. A heat-sensitive stencil paper having a coating layer was obtained. 0.1 g/n4 of silicone oil was applied as a release layer to the coated layer surface of this heat-sensitive stencil paper.
Wire barcode was performed so that

Example 2 Ethylcellulose (ethoxyl content 48% by weight, average molecular weight 11100.ooO) and cellulose acetate butyrate (acetyl content 2.0% by weight, butyryl content 53% by weight, average molecular weight 30.00) were used as polymer solutions.
2% by weight of toluene in a mixed resin with a weight ratio of 6:4
A thermal stencil paper was prepared in the same manner as in Example 1, except that a methyl isobutyl ketone solution was used, the drying conditions after coating were 80° C. for 1 minute, and the dry thickness was approximately 1 μm. A similar silicone coating was applied.

Comparative Example 1 A 2% by weight toluene solution of ethyl cellulose (the same as that used in Example 1) was used as the polymer solution, the drying conditions after application were 80°C for 1 minute, and the dry thickness was approximately 1%.
A heat-sensitive stencil paper was prepared in the same manner as in Example 1, except that the thickness was set to μm, and the same silicone coating as in Example 1 was applied.

Comparative Example 2 A 2% by weight methyl isobutyl ketone solution of nitrocellulose (the same as that used in Example 1) was used as the polymer solution, and the drying conditions after application were 80°C for 1 minute.
A heat-sensitive stencil paper was prepared in the same manner as in Example 1, except that the dry thickness was about 1 μm, and the same silicone coating as in Example 1 was applied.

Comparative Example 3 A 211!1% solution of cellulose acetate butyrate (same as used in Example 2) in methyl isobutyl ketone was used, and the drying condition after application was 80° C. for 1 minute.
A heat-sensitive stencil paper was prepared in the same manner as in Example 1, except that the dry thickness was about 1 μm, and the same silicone coating as in Example 1 was applied.

In order to examine the printing performance of the heat-sensitive stencil papers of the above Examples and Comparative Examples, a 12 dot/Iu thermal recording head was used, and the heating element was set so as to hit the coated layer surface of each base paper, and an applied voltage of 25 V was applied.

A plate was made under printing conditions with an application time of 2 m5 eC, and then printing was performed using a stencil printing machine (trade name: AP7200, manufactured by Riso Kagaku Kogyo Co., Ltd.).

As a result, on the base paper of Comparative Example I, characters dragged due to sticking, and on the base paper of Comparative Example 2. Very high-density printing was possible with no broken or blurred characters, and no scratching of characters due to sticking was observed.

From these results, it is clear that the heat-sensitive stencil paper of the present invention has excellent printing sensitivity and staking resistance.

Claims (1)

[Claims] (1) A heat-sensitive stencil paper characterized in that a polymer coating layer mainly composed of a mixed resin of ethyl cellulose, nitrocellulose and/or cellulose acetate butyrate is provided as a heat-sensitive stencil layer on one side of a porous thin sheet material.